Practice keyboard



Oct. 10, 1950 5. TATNALL 2,525,188

PRACTICE Filed April 1, 1948 $2 & Z0 Z1 Z3 Z1 Z0 INVENTO Josey/LSTaUzaZZ of a loose pivot.

Patented Oct. 10, 1950 I PRACTICE KEYBOARD Joseph S. Tatnall, GordonHeights, Del., as-

signor to Audiscope Corporation, a corporation of Delaware ApplicationApril 1, 1948, Serial No. 18,451

simulating the appearance and actionof the key board of a completepiano. Such devices are particularly intended'for piano instruction andpractice in situations where it would be impractical or undesirable toemploy a full, tuned piano. For example, piano students may receivegroup instruction in finger movements, each being provided with such apractice key board, or expert players may employ them for exercisepurposes, when a complete piano is not available or its sound mightdisturb others.

It is most important that such a practice key board be substantiallyidentical in action or feel with the key board of a full, tuned piano,otherwise much of its value would be lost. Fu thermore, it must bedurable and yet inexpensive and light in weight, in order to assure itsWidespread use. It is the object of my invention to provide such adevice that combines all of these desired characteristics. Y

The principal feature of my invention has to do with the particularmeans employed to produce a tension upon the keys of .the practice keyboard, that is substantially identical with the tension under which thekeys of a full, tuned piano are held, therebyto imitate closely theaction or feel of the piano key board. Many attempts have been made toreproduce such tension by means of various types of metalsprings,

rubber bands, sponge rubber and the like, but none have proven to be assimple, durable and effective as the means which I have devised.

Afurther feature of my invention concerns the location of my noveltensioning means, whereby they also serve to hold the keys of mypractice key board in proper alignment, despite the use Yet anotherfeature resides in the manner in which such tensioning means are mountedin the practice key board, -making it very easy to install and toreplace them as desired. These features of my invention may beembodiedgin the practice key board singly and in combination toaccomplish the object of my invention.

My novel tensioningmeans consist of short sections of rubber tubing,which are compressed axially as the keys of the practice key board aredepressed. Such rubber tube sections are remarkably uniform and durablein action. It is possible to regulate the degree and kind of tensionthereby exerted upon the keys, by varying their diameter, wall thicknessor length. The

type of resilient material employed, which Heed not necessarily benatural rubber, is also a factor,

9 Claims. (Cl. 84-467) but given any suitable resilient material, it iseasy to reproduce precisely the desired kind and degree of tension byproper selection of the other factors mentioned.

As previously indicated, the location of my novel tensioning meanswithin the practice key board is important for optimum results. I havefound that by causing them to bear against the backs of the keys at apoint'below the pivot of the keys, they tend to push the keys forwardagainst such pivot and to hold them in proper alignment, even though thekeys fit loosely about said pivot. It is highly desirable from amanufacturing standpoint and from the standpoint of simulating theaction of piano keys, to employ such a loose pivot,

I have found that my novel tensioning means can be very easilymountedupon a metalplate along the back of the practice key board, whichmetal plate has a series of up-struck inner pro jections about which therubber tube sections are simply fitted and to which they hold by theirown resiliency. The up-struck projecting portions of the metal backplate serve to support the rubber tube sections at exactly the desiredlocations. This is important, when one considers that a separatetensioning means is provided for'each individual key, so that the actionof one key will not affect that of any other. A great advantage achievedby this manner of mounting the tensioning means, is that they can beinstalled and replaced as desired simply by slipping them over theup-struck projections on the metal back plate.

In other respects my practice key board is of more or lessconventionalconstruction. It includes the usual set of long white andshort black keys of the same dimensions as in the key board of a piano,except that ordinarily the practice key board is limited to but a fewoctaves, in

order to reduce its length without unduly reducing its utility as apractice instrument. The keys are all pivoted on a single rod or shaftlocated near the back of the device, which is supported at severalpoints along its length to assure ample rigidity. Cushioned stops areprovided to limit the movement of the keys about the pivot and to rendertheir action noiseless. A case is generally provided, which is similarin appearance to that surrounding the key board of a regular piano. I

In the accompanying drawings, I have illustrated a preferred embodimentof my invention including the various features generally referred toabove. In these drawings:

Figure 1 is a plan view of a portion (two octaves) of a practice keyboard according to my invention. The top portion of the usual case hasbeen removed in order to show my novel tensioning means mounted upon themetal back plate;

Figure 2 is a sectional view on the line 2-2 of Figure l and;

Figure 3 is another sectional view of a portion of my device along theline 3-3 of Figure 2.

As shown by these drawings, the long white keys I and the short blackkeys I I are supported at the back by a common pivot l'2 which extendsacross the entire length of the key board. This pivot is preferablycomposed of a metal rod or a shaft which is supported at each end and atseveral points along its length to impart sufficient rigidity. It passesthrough holes in the keys and should fit rather loosely for ease inmanufacture and assembly and for freedom of action of the keys. The arcsin which the keys may swing about the pivot are limited by the stops I3,I4, I5 and IS, which are composed of resilient material, such as arubber tube, in order to render the key board soundless. the movement ofthe white keys I0, while stops I5 and IE limit that of the black keys.The white keys H3 are provided with a projection I! at the bottom frontportion to act upon the stop I3. Stop I6 is located upon a raised baseI8, in order that the black keys II may not be depressed below thedesired point.

All of the keys Ii! and H are provided with downwardly extendingportions I9 at the back against which my novel tensioning means arecaused to act. These tensioning means consist of short sections ofrubber or like resilient tubing 26 and 2|. Since the black keys II areshorter and swing through a greater arc than the white keys IE), it isbest to compensate for these differences by employing resilient tubesections of slightly different diameters and wall thicknesses. In thekey board shown, the tube sections 2! act ing upon the black keys areslightly larger in diameter and have greater wall thickness than thetube sections 2!] acting upon the white keys.

The method of mounting my novel tensioning means at the desiredlocations can best be seen from Figure 2. Up-struck projections 22 arepro vided in the metal back plate 23 by a simple stampin operation.These projections are of such width that the resilient tube sectionswill fit snugly thereover. No adhesive need be employed, thus greatlysimplifying the task of installing or replacing the tensioning means.The projections 22 do not extend far enough within the resilient tubesections 28 and 2| to interfere with the tensioning action of thelatter.

It should be noted that the tensioning means and 2! are normally undersufficient compression to force the keys I D and I I against the stopsI3 and I5, respectively. These tensioning means are centered in back ofeach individual key, thus tending to force it forward against the pivotI2. As a result, the tensioning means tend to keep the keys in properalignment, even though a loose pivot is employed.

The case of my practice key board may be made of a single sheet of metalas shown, or the metal back plate 23 may be mounted within a separatewooden casing, if desired. Many other variations are, of course,possible without departing from the principles of my invention. Theinvention is not limited to the details shown and includes all The stopsI3 and I4 limit such modifications as are embraced within the scope ofthe appended claims.

I claim:

1. A practice key board comprising a set of pivotally mounted keys andtensioning means urging the front ends of the keys upwards, saidtensioning means consisting of short, resilient tube sections fixedlysupported at one end within the device which are compressed axially,when the front ends of the keys are depressed.

2. A practice key board comprising a set of keys, all mounted on ahorizontal pivot, and separate tensioning means for each key urging itsfront end upwards, said tensioning means consisting of a short,resilient tube section fixedly supported at one end within the devicewhich is compressed axially, when the front end of the key is depressed.

-3. A practice key board comprising a set of keys, pivotally mountednear the back of the device, and short, axially compressed tube sectionsof resilient material fixedly supported at one end within the device andwhose other ends bear against the backs of said keys below their pivot.

4. A practice key board comprising a set of keys, all mounted on ahorizontal pivot rod near the back of the device, and a correspondingset of short, axially compressed tube sections of resilient materialmounted upon a back plate, each tube section bearing against the back ofa key below the pivot rod.

5. A practice key board comprising a set of keys, pivotally mounted nearthe back of the device, and short, axially compressed tube sections ofresilient material mounted over inwardly projecting, up-struck portionsof a metal back plate and bearing against the backs of the keys belowtheir pivot.

6. A practice key board comprising a set of white and black keys, allmounted on a horizontal pivot rod near the back of the device, and acorresponding set of short, axially compressed, rubber tube sections,all fitting snugly over inwardly projecting, up-struck portions of ametal back plate, each tube section being centered in back of a key andbearing against a downwardly extending portion thereof.

7. A practice key board as claimed in claim 6, wherein the diameter andwall thickness of the tube sections bearing against the black keys arelarger than those of the tube sections bearing against the white keys.

8. A practice key board comprising a set of keys, all pivotally mountednear the back of the device, and short, compressible, resilient membersfixedly supported at one end within the device and whose other ends bearagainst the backs of said keys below their pivot.

9. A practice key board comprising a set of keys, all loosely mounted ona horizontal pivot rod near the back of the device, and a correspondingset of short, compressible, resilient members mounted at one end upon aback plate, the other end of each of said members bearing against theback of a key below the pivot rod.

JOSEPH S. TATNALL.

Country Date Great Britain June 23, 1937 Number

